Warships and fighter jets of the Chinese People's Liberation Army Navy take part in a military display in the South China Sea on April 12, 2018.

CHINA STRINGER NETWORK/Reuters

Two years after an international court struck down China’s dotted lines in the South China Sea as being “without lawful effect,” Chinese researchers have published details of a historical map that, they say, demonstrates a “border” in waters whose ownership is hotly disputed.

The newly unearthed 1951 map, called the New Map of the People’s Republic of China, shows a continuous maritime line that extends far south of the Chinese mainland, looping around virtually the entire South China Sea, one of the world’s most important ocean-shipping bodies. The line comes within a hair of Malaysian Borneo, Brunei and the Philippines, and takes in Taiwan as well as many of the waters and ocean features whose ownership is also claimed by China’s neighbours.

The researchers call it “the South China Sea U-Shape boundary line,” and recommend its use to “further express the certainty of the integrity, continuity and border of China’s seas.”

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The report is an academic one, and not Chinese government policy. But it suggests a new foundation for China to assert ownership of a vast region in which it has already spent heavily to build and equip artificial islands for military use, raising the fury of some neighbours in the process.

The U-shaped line has “a very high probative value for China’s claim to South China Sea sovereignty,” the researchers, some affiliated with the Chinese Academy of Sciences, write in the paper, published last month by Science China Press.

“Our thesis simply points out the objective facts,” said Hao Xiaoguang, a researcher at the academy’s Institute of Geodesy and Geophysics, and one of the study’s authors.

“It’s unwise to think or to imply that our study is motivated by a certain political purpose.”

But, ”safeguarding national sovereignty, as a Chinese scientist – surely we all have this hope,” he added.

The 1951 map, he said, came from Yang Lang, a columnist and map collector who is currently cultural and artistic director at HNA Group, a heavy-spending Chinese company that has amassed both worldwide assets and scrutiny, the latter for the opacity of its ownership structure.

Mr. Hao said he has “no interest” in how Mr. Yang acquired the map. “This is not a meaningful question, though I know you journalists always love asking these kinds of questions – the gossip and anecdotes. I don’t care about that,” Mr. Hao said. Mr. Yang could not be reached for comment.

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Publication of the map research comes as China continues to push its maritime ownership claims on numerous fronts. Last week, Chinese vessels sank a Vietnamese fishing boat not far from the Paracel Islands, local media reported. Both Vietnam and China claim those islands.

In Manila, meanwhile, authorities have said they are looking into reports that Chinese military aircraft have landed on an artificial island inside the Philippines’ exclusive economic zone. China has transformed reefs in the Spratly Archipelago into what local media in the Philippines have now dubbed “island fortresses.”

Bill Bishop, a long-time China observer and author of the Sinocism newsletter, lists “full control of the South China Sea” as a central objective for Chinese President Xi Jinping.

Chinese authorities have ignored the ruling in 2016 by the Permanent Court of Arbitration, which took specific aim at “China’s claims to historic rights, or other sovereign rights or jurisdiction, with respect to the maritime areas of the South China Sea encompassed by the relevant part of the ‘nine-dash line.’” Those claims are “without lawful effect,” the court found.

“The new unofficial maritime boundary is the latest attempt by China to quietly walk back from a clear cut and humiliating legal defeat,” said Richard Heydarian, a Manila-based scholar and author of Asia’s New Battlefield: US, China & Struggle for Western Pacific.

“I see this new ’discovery’” – the 1951 map – “as a new attempt to sell an old discredited body of claims which were struck down with finality by the arbitral ruling in 2016,” he said. “You don’t own international waters and features a thousand kilometres away from your shores based on obscure maps.”

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But for Beijing, open discussion of a solid maritime borderline can be seen as a sign of confidence that it has managed to build a significant territorial position in the South China Sea. It amounts to ”signalling the fact that they’ve effectively changed the status quo in this region – and you’re basically going to have to accept it,” said J. Berkshire Miller, international affairs fellow with the Council on Foreign Relations in Tokyo.

Still, maps in themselves aren’t as authoritative as they may look.

“Antique and vintage maps are interesting and helpful tools that reflect the cartographer’s views at the time of creation,” said James Zimmerman, a lawyer in Beijing who collects antique maps from Asia and China.

“But they’re just one tool and not determinative, by themselves, of historical territorial claims to seas beyond national jurisdiction of coastal nations.”

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